JP4286030B2 - Method for producing vapor grown carbon fiber - Google Patents

Description

【００４０】
＜実施例５、６＞
窒素ガスの代わりに、表２に示したガスを、表２に示した流速で用いた以外は、実施例２と同様にして反応を行い、生成物を観察した。
【００４１】
【表２】

【００４２】
＜実施例７、８、比較例４、５＞
表３に示したキャリアガスおよび、加熱帯域の温度以外は、実施例２と同様に実施した。
【００４３】
【表３】

【００４４】
【発明の効果】
上述したように本発明によれば、キャリアガス中の還元ガス濃度を最適化し、使用する触媒量に応じて、キャリアガス中の還元ガス濃度を調製することによって、炭素回収率を向上させ、効率的且つ安価に炭素繊維を製造することができる。
【図面の簡単な説明】
【図１】炭素繊維を製造するための横型反応器の一般的な例を示す模式断面図である。
【図２】実施例、比較例で炭素繊維を製造した縦型反応器を示す模式断面図である。
【符号の説明】
１…横型環状炉
２…反応管
３…回収容器
１１…原料噴霧ノズル
１２…反応管
１３…縦型環状炉
１４…回収容器[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method capable of efficiently producing vapor grown carbon fibers (for example, carbon nanotubes).
[0002]
[Prior art]
Since carbon fibers typified by carbon nanotubes have useful applications such as various composite materials with metals, synthetic resins, etc., methods for producing these carbon fibers (for example, a gas phase method, a substrate method, etc.) have hitherto been used. It has been actively researched and therefore has many reports.
[0003]
Among the methods for producing carbon nanotubes, it is known industrially that the gas phase method can produce carbon fibers at the lowest cost. There are various embodiments of the carbon fiber production method of such a gas phase method. In the carbon fiber production method of the gas phase method, any of the carbon compound as a carbon source and a catalyst is used as a carrier. It is common in the point of making it react in a high temperature reactor using gas. In the examination of such a production method, reports on carbon compounds, catalysts, and reaction forms thereof have been widely made, but few have focused on carrier gas.
[0004]
For example, JP 59-152299 A (Patent Document 1) proposes using a mixture of hydrogen and an inert gas as a carrier gas. In this document, the range of inert gas / hydrogen gas = 30/70 to 0/100 is preferred, but according to the example of the document, the hydrogen concentration in the carrier gas is reduced by the reaction at 1160 ° C. It has been disclosed that the yield decreases, and a higher hydrogen gas concentration is advantageous.
[0005]
Japanese Patent Laid-Open No. 63-282313 (Patent Document 2) states that the carrier gas is preferably 30% by volume or more of hydrogen gas, particularly preferably 50% by volume or more, but there is no example. Therefore, the contents are unclear, and the effect is not clarified.
[0006]
[Patent Document 1]
JP 59-152299 A
[Patent Document 2]
JP-A 63-282313
[0007]
[Problems to be solved by the invention]
The objective of this invention is providing the manufacturing method which can improve the conversion rate (yield) of a raw material hydrocarbon to carbon fiber in manufacture of the carbon fiber by a gaseous-phase method.
[0008]
[Means for Solving the Problems]
As a result of intensive studies on the effect of the carrier gas in the gas phase method, the present inventors have found that the reducing gas concentration in the carrier gas greatly affects the yield, and have completed the present invention. That is, the present invention relates to the following [1] to [8].
[0009]
[1] In a method for producing carbon fiber by contacting a carbon compound and a catalyst in a heating zone in the presence of a carrier gas containing a reducing gas;
A method for producing vapor-grown carbon fibers, wherein the reducing gas concentration in the carrier gas is 30% by volume or more and less than 100% by volume, and the temperature in the heating zone is 1165 ° C to 1500 ° C.
[0010]
[2] In a method for producing carbon fiber by contacting a carbon compound and a catalyst in a heating zone in the presence of a carrier gas containing a reducing gas;
A method for producing vapor grown carbon fiber, characterized in that the reducing gas concentration in the carrier gas is 30% by volume or more and less than 100% by volume, and the catalyst is continuously supplied.
[0011]
[3] The method for producing vapor-grown carbon fiber according to [1] or [2], wherein the concentration of the reducing gas in the carrier gas is 30% by volume to 90% by volume.
[0012]
[4] In a method for producing carbon fiber by contacting a carbon compound and a catalyst in a heating zone in the presence of a carrier gas containing a reducing gas;
A method for producing vapor-grown carbon fiber, wherein the logarithmic ratio of the catalyst metal concentration and the reducing gas concentration represented by the following formula is 5 or more and 340 or less.
[0013]
(Logarithmic ratio of catalyst metal concentration and reducing gas concentration) = log (molar fraction of catalytic metal in reaction system) / log (molar fraction of reducing gas in reaction system)
[5] In a method for producing carbon fiber by bringing a carbon compound and a catalyst into contact in a heating zone in the presence of a carrier gas containing a reducing gas;
The reducing gas concentration in the carrier gas is 30% by volume or more and less than 100% by volume, the temperature of the heating zone is 1165 ° C. to 1500 ° C., and the logarithmic ratio of the catalytic metal concentration and the reducing gas concentration shown in the following formula is 5 or more and 340 The manufacturing method of the vapor grown carbon fiber characterized by the following.
[0014]
(Logarithmic ratio of catalyst metal concentration and reducing gas concentration) = log (molar fraction of catalytic metal in reaction system) / log (molar fraction of reducing gas in reaction system)
[6] Production of vapor grown carbon fiber according to any one of [1] to [5], wherein the reducing gas is at least one selected from the group consisting of hydrogen, carbon monoxide, and ammonia gas. Method.
[0015]
[7] The carbon compound includes at least one selected from the group consisting of carbon monoxide, methane, ethane, propane, butane, ethylene, propylene, butadiene, acetylene, benzene, toluene, and xylene. [1] A method for producing vapor grown carbon fiber according to any one of [5].
[0016]
[8] The gas phase method according to any one of [1] to [5], wherein the catalyst includes at least one element selected from the group consisting of Group 3 to 12 elements in the group 18 element periodic table. A method for producing carbon fiber.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described more specifically with reference to the drawings as necessary. In the following description, “%” representing the quantitative ratio is based on mass unless otherwise specified.
(Method for producing vapor grown carbon fiber)
In the method for producing vapor grown carbon fiber of the present invention, the feature is to reduce the concentration of reducing gas in the carrier gas, thereby suppressing the production of by-products such as methane and improving the yield. is there. In the prior art, as described in Patent Document 1 described above, it has been said that a reduction in reducing gas concentration causes a reduction in yield. In contrast, the present inventor has found that the yield can be improved in a specific concentration range by appropriately controlling the reaction conditions.
(Carrier gas)
In the present invention, a mixture of a reducing gas and an inert gas component can be used as the carrier gas.
(Reducing gas)
The reducing gas is not particularly limited as long as it is a gas having a general reducing ability such as hydrogen, carbon monoxide, and ammonia. A mixture of two or more of these can also be preferably used. As the reducing gas, hydrogen is particularly preferable from the viewpoint of cost and safety. Carbon monoxide also acts as a carbon compound as a raw material for carbon fibers.
(Inert gas)
Although it does not specifically limit as an inert gas, From a cost and versatility point, nitrogen, argon, helium, krypton, carbon dioxide, and these 2 or more types of mixtures can be used. When carbon dioxide is used, it may work as a carbon compound.
(Heating zone)
In the production method of the present invention, carbon fibers are produced by bringing a carbon compound and a catalyst into contact with each other in a heating zone in the presence of a carrier gas containing a reducing gas. The temperature in this heating zone depends on the carbon compound and catalyst used to some extent, but is usually carried out at 1200 to 1400 ° C. However, the present invention is effective at 1165 to 1500 ° C., particularly 1200 to 1300 ° C. If the temperature in the heating zone is 1165 low, the yield decreases. On the other hand, if the temperature in the heating zone is higher than 1500 ° C., the mixture of spherical carbon into the product becomes remarkable, which is not preferable.
(Reducing gas concentration)
The concentration of the reducing gas in the carrier gas is preferably 30% by volume to less than 100% by volume, more preferably 30 to 80% by volume, and most preferably 35 to 70% by volume. The preferred concentration range of the reducing gas varies depending on the amount of the catalyst metal used, and the logarithmic ratio (hereinafter referred to as “concentration ratio”) of the catalyst metal concentration and the reducing gas concentration represented by the following formula is 5 or more, 340 The following are preferable, 5 to 50 are more preferable, and 12 to 50 are optimal.
[0018]
(Log ratio of catalyst metal concentration and reducing gas concentration) = log (molar fraction of catalytic metal in reaction system) / log (molar fraction of reducing gas in reaction system)
If the reducing gas concentration is higher than 80% by volume or the concentration ratio is higher than 50, the yield tends to decrease. On the other hand, when the concentration ratio is lower than 5, spherical carbon particles are the main component in the product, which is not preferable.
(Carbon compound)
As a carbon compound used as a raw material of carbon fiber, CCl _Four , CHCl _Three , CH ₂ Cl ₂ , CH _Three Cl, CO, CO ₂ , CS ₂ Etc. can be suitably used. In addition, these other organic compounds in general can also be used. Particularly useful compounds are CO and CO from the viewpoint of cost and versatility. ₂ , Aliphatic hydrocarbons and aromatic hydrocarbons.
[0019]
In addition to these, carbon compounds containing elements such as nitrogen, phosphorus, oxygen, sulfur, fluorine, chlorine, bromine and iodine can also be used. It is also possible to make these carbon compounds gaseous and supply them to the reactor.
[0020]
Examples of preferred carbon compounds include CO, CO ₂ Inorganic gases such as methane, ethane, propane, butane, pentane, hexane, heptane, octane, etc .; alkenes such as ethylene, propylene, butadiene; alkynes such as acetylene; benzene, toluene, xylene, styrene, etc. Monocyclic aromatic hydrocarbons; polycyclic compounds having condensed rings such as indene, naphthalene, anthracene, phenanthrene; cycloparaffins such as cyclopropane, cyclopentane, cyclohexane; cyclopentene, cyclohexene, cyclopentadiene, dicyclopentadiene, etc. And cycloaliphatic hydrocarbon compounds having a condensed ring such as steroid.
[0021]
Further, derivatives containing oxygen, nitrogen, sulfur, phosphorus, halogen, etc. in these hydrocarbons, for example, oxygen-containing compounds such as methanol, ethanol, propanol, butanol; methylthiol, methylethyl sulfide, dimethylthioketone, etc. Sulfur-containing aliphatic compounds; sulfur-containing aromatic compounds such as phenylthiol and diphenylsulfide; sulfur- or nitrogen-containing heterocyclic compounds such as pyridine, quinoline, benzothiophene, and thiophene; chloroform, carbon tetrachloride, chloroethane, trichloroethylene, etc. Although not a simple substance, natural gas, gasoline, kerosene, heavy oil, creosote oil, kerosene, turpentine oil, camphor oil, pine oil, gear oil, cylinder oil and the like can also be used. It is of course possible to use a mixture of these.
[0022]
More preferred carbon compounds in terms of carbon fiber-forming ability and cost include CO, methane, ethane, propane, butane, ethylene, propylene, butadiene, acetylene, benzene, toluene, xylene and mixtures thereof.
(catalyst)
The catalyst to be used in the production method of the present invention is not particularly limited as long as it is a substance that promotes the growth of carbon fibers. Suitable catalysts include catalysts containing at least one metal selected from the group consisting of groups 3 to 12 in the group 18 element periodic table recommended by IUPAC in 1990. Furthermore, a catalyst containing at least one metal selected from the group consisting of 3, 5, 6, 8, 9, 10 groups is preferable, and a catalyst containing iron, nickel, cobalt, ruthenium, rhodium, palladium, platinum and rare earth elements. Is particularly preferred.
(Catalyst precursor compound)
Instead of the above-mentioned catalyst or in combination with the above-mentioned catalyst, a catalyst precursor compound that can be thermally decomposed in a heating zone and further reduced in some cases to give the above-mentioned catalyst may be used as a starting material. Is possible. The “catalyst” referred to in the claims includes a catalyst precursor compound.
[0023]
As an example of such a catalyst precursor compound, for example, ferrocene is thermally decomposed in a heating zone to produce iron fine particles as a catalyst. Therefore, as the catalyst precursor compound, a compound that gives a metal as shown in the explanation of the “catalyst” can be preferably used. More specifically, a metal compound containing at least one element selected from the group consisting of Groups 3 to 12 of the Group 18 element periodic table is preferable, and further, Groups 3, 5, 6, 8, 9, and 10 are preferable. A compound containing at least one element selected from the group consisting of iron, nickel, cobalt, ruthenium, rhodium, palladium, platinum and a rare earth element is most preferable.
[0024]
In addition, a metal compound containing at least one element selected from the group consisting of groups 1 to 17 is added to these main components as a catalyst modifying component (so-called co-catalyst) to modify the catalytic performance of the main component metal. It is also possible to do.
(Carrier)
The above-described catalyst and / or catalyst precursor compound can be used by being supported on a carrier as necessary. These carriers are preferably compounds that are stable in the heating zone, and examples of these compounds include alumina, silica, zeolite, magnesia, titania, zirconia, graphite, activated carbon, and carbon fiber.
(Amount of catalyst used)
The amount of the catalyst or catalyst precursor compound used is preferably from 0.000001 to 1, more preferably from 0.00001 to 0.1, in terms of the ratio of the number of moles of catalyst metal to the number of moles of carbon in the carbon compound. 0.0001 to 0.005 is optimal. If the molar ratio is less than 0.000001, the catalyst is insufficient, and the number of carbon fibers tends to decrease or the carbon fiber diameter tends to increase. On the other hand, it is not preferable that the ratio of the number of moles is greater than 1, because not only is it economical, but also coarsened catalyst particles that do not function as a catalyst tend to be mixed in the carbon fiber. In addition, in calculation of the carbon atom mole number ratio in said carbon compound, not only a carbon compound but the carbon atom derived from a catalyst precursor compound or a solvent shall be included.
(Sulfur compound)
In the present invention, a sulfur compound which is considered to be effective in controlling the carbon fiber diameter may be used in combination as necessary. A compound such as sulfur, thiophene, hydrogen sulfide or the like can be used in the form of a gas and used as one component of the carrier gas, or may be supplied after being dissolved in a solvent. Of course, a substance containing sulfur in the carbon compound and the catalyst precursor compound may be used.
[0025]
The total number of moles of sulfur to be supplied is 1000 times or less, preferably 100 times or less, more preferably 10 times or less the number of moles of metal in the catalyst. An excessive amount of sulfur to be supplied is not preferable because it is not economical and tends to hinder the growth of carbon fibers.
(Additive ingredients)
Furthermore, it is also possible to add an additive component having an effect of improving the yield of carbon fiber as necessary. As this additive component, either an organic compound or an inorganic compound can be used.
(Organic compounds)
Examples of organic compounds that can be used as such additive components include saturated and unsaturated hydrocarbons having 10 or more carbon atoms and higher alcohols, olefins, halogenated ethylenes, dienes, acetylene derivatives, styrene derivatives. , Vinyl ester derivatives, vinyl ether derivatives, vinyl ketone derivatives, acrylic acid / methacrylic acid derivatives, acrylic acid ester derivatives, methacrylic acid ester derivatives, acrylamide / methacrylamide derivatives, acrylonitrile / methacrylonitrile derivatives, maleic acid / maleimide derivatives, vinylamine derivatives, Selected from the group consisting of phenol derivatives, melamines / urea derivatives, amine derivatives, carboxylic acid / carboxylic acid ester derivatives, diol / polyol derivatives, isocyanate / isothiocyanate derivatives At least one organic compound and a polymer thereof can be cited are.
[0026]
More preferable compounds as the additive component include octyl alcohol, decyl alcohol, cetyl alcohol, stearyl alcohol, oleic acid, stearic acid, adipic acid, linoleic acid, erucic acid, behenic acid, myristic acid, lauric acid, capric acid, and caprylic acid. , Hexanoic acid and their sodium, potassium salts, dimethyl malonate, dimethyl maleate, dibutyl phthalate, ethyl hexyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dibutoxyethyl phthalate, phthalate Ethyl hexyl benzyl, ethyl hexyl adipate, diisononyl adipate, diisodecyl adipate, dibutoxyethyl adipate, ethyl hexyl trimellirate, polyethylene glycol Polypropylene glycol, polyoxyethylene glycol monomethyl ether, polyoxyethylene glycol dimethyl ether, polyoxyethylene glycol glycerin ether, polyoxyethylene glycol lauryl ether, polyoxyethylene glycol tridecyl ether, polyoxyethylene glycol cetyl ether, polyoxyethylene Glycol stearyl ether, polyoxyethylene glycol oleyl ether, polypropylene glycol diallyl ether, polyoxyethylene glycol nonyl phenyl ether, polyoxyethylene glycol octyl ether, polypropylene glycol stearate, sodium di-2-ethylhexyl sulfosuccinate, polyethylene oxide, polypropylene Koxide, polyacetal, polytetrahydrofuran, polyvinyl acetate, polyvinyl alcohol, polymethyl acrylate, polymethyl methacrylate, polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyurethane, unsaturated polyester, epoxy resin, phenol resin, polycarbonate, Polyamide, polyphenylene oxide, polyacrylonitrile, polyvinyl pyrrolidone and the like can be mentioned.
(Inorganic compounds)
Examples of inorganic compounds that can be used as the additive component include inorganic compounds containing at least one element selected from the group consisting of Group 2 to 15 elements in the Group 18 element periodic table, more preferably Mg, Ca, Inorganic compound containing at least one selected from the group consisting of Sr, Ba, Y, La, Ti, Zr, Cr, Mo, W, Fe, Co, Ni, Cu, Zn, B, Al, C, Si, Bi Is good.
[0027]
Although these metals can be used alone, they are generally unstable and have problems in handling and stability, so that they can be used as oxides, nitrides, sulfides, carbides and their double salts. Recommended. Further, sulfates, nitrates, acetates, hydroxides and the like that can be decomposed by heating to become these compounds may be used.
[0028]
Furthermore, carbon may be used alone as an additive component, and activated carbon, graphite and the like can also be used effectively. Carbon fiber itself can also be used as an additive component, but in view of the convenience of supply, those having a large aspect ratio are not suitable, the aspect ratio is 1 or more and 50 or less, and the average fiber diameter is It is preferably 10 nm or more and 300 nm or less (the aspect ratio is measured by the fiber diameter and the fiber length using an electron micrograph, and is obtained by the fiber length / fiber length).
[0029]
These inorganic compounds include zinc oxide, aluminum oxide, calcium oxide, chromium oxide (II, III, VI), cobalt oxide (II, III), cobalt oxide (II) aluminum, zirconium oxide, yttrium oxide, silicon dioxide, Strontium oxide, tungsten oxide (IV, VI), titanium oxide (II, III, IV), iron oxide (II, III), iron oxide (III) zinc, iron oxide (III) cobalt (II), iron oxide (III ) Iron (II), iron (III) copper (II), copper oxide (I, II), iron (III) barium, nickel oxide, nickel (II) iron (III) oxide, barium oxide, barium aluminum oxide Bismuth oxide (III), bismuth oxide (IV) dihydrate, bismuth oxide (V), bismuth oxide (V) Hydrates, magnesium oxide, magnesium aluminum oxide, magnesium iron (III) oxide, molybdenum oxide (IV, VI), lanthanum oxide, lanthanum iron oxide, zinc nitride, aluminum nitride, calcium nitride, chromium nitride, zirconium nitride, titanium nitride , Iron nitride, copper nitride, boron nitride, zinc sulfide, aluminum sulfide, calcium sulfide, chromium sulfide (II, III), cobalt sulfide (II, III), titanium sulfide, iron sulfide, copper sulfide (I, II), sulfide Nickel, barium sulfide, bismuth sulfide, molybdenum sulfide, zinc sulfate, zinc ammonium sulfate, aluminum sulfate, ammonium aluminum sulfate, ammonium chromium sulfate, yttrium sulfate, calcium sulfate, chromium sulfate (II, III), cobalt sulfate (II), titanium sulfate ( III IV), iron sulfate (II, III), ammonium iron sulfate, copper sulfate, nickel sulfate, nickel ammonium sulfate, barium sulfate, bismuth sulfate, magnesium sulfate, zinc nitrate, aluminum nitrate, yttrium nitrate, calcium nitrate, chromium nitrate, nitric acid Cobalt, zirconium nitrate, bismuth nitrate, iron nitrate (II, III), copper nitrate, nickel nitrate, barium nitrate, magnesium nitrate, manganese nitrate, zinc hydroxide, aluminum hydroxide, yttrium hydroxide, calcium hydroxide, chromium hydroxide (II, III), cobalt hydroxide, zirconium hydroxide, iron hydroxide (II, III), copper hydroxide (I, II), nickel hydroxide, barium hydroxide, bismuth hydroxide, magnesium hydroxide, zinc acetate , Cobalt acetate, copper acetate, nickel acetate, iron acetate, active Examples include charcoal, graphite, carbon fiber, zeolite (aluminosilicate), calcium phosphate, and aluminum phosphate.
[0030]
An example of the most preferred additive component of the inorganic compound is activated carbon, graphite, silica, alumina, magnesia, titania, zirconia, zeolite, calcium phosphate, which is easily available in industrial form and preferably has an average particle size of 100 μm or less. , Aluminum phosphate, and carbon fibers having an aspect ratio of 50 or less.
(Method for producing carbon fiber)
The method for producing carbon fiber is not particularly limited as long as it is a method generally used for synthesis of carbon fiber by a gas phase method. From the viewpoint of versatility and economy, as an example, a reactor as shown in FIG. 1 can be suitably used.
[0031]
A reaction tube 2 made of quartz or ceramics such as silicon carbide is installed in a horizontal annular furnace 1, and a carrier gas mixed in advance is introduced from the inlet.
[0032]
An appropriate supply method can be selected depending on the form of the catalyst source and the raw material hydrocarbon. If the raw material carbon compound is a gas at normal temperature, supply it as a gas mixed with a carrier gas. If it is a liquid, supply it after being vaporized and then mixed with the carrier gas, or spray it in a liquid state in the heating zone. Is preferred. When a supported catalyst is used as the catalyst, it is preferable that the supported catalyst is installed in the reaction zone in advance and heated to perform the necessary pretreatment and then the raw material carbon compound is supplied. More preferably, the pretreated supported catalyst is supplied continuously or pulsed from outside the system.
[0033]
A method or catalyst in which a catalyst or catalyst precursor compound is dissolved in a raw liquid carbon compound, or dissolved in an appropriate solvent, and fed continuously or in a pulsed manner to a heating zone, or a catalyst precursor compound is directly vaporized or A method in which the solid is continuously fed to the heating zone continuously or in a pulse manner is most preferable.
(Aspect for supplying catalyst precursor compound)
The effect of the present invention appears most remarkably when an organometallic compound such as ferrocene is continuously supplied to the reactor together with the raw material carbon compound as a catalyst precursor compound. In such a system, the catalyst particles produced from the precursor compound are present in the reaction zone in a highly dispersed state, and therefore, the effect of suppressing the conversion of the raw material carbon compound to methane to become a solid carbon compound. Contributes to the improvement of the carbon fiber yield as it is, so that the effect of the present invention is most prominent. Even in the so-called substrate method in which the reaction zone is preliminarily filled with a catalyst, the yield improvement effect of the present invention can be expected. However, in a system in which the catalyst is not continuously supplied, the catalyst and the carbon compound or a decomposition product thereof Since the contact efficiency largely controls the yield, the effect tends to be relatively limited.
(Reactor)
The type of the reactor is not particularly limited, and those generally used for the production of carbon fibers can be used as long as a predetermined heating zone temperature and residence time can be obtained. From the viewpoint of versatility and economy, a horizontal reactor or a vertical reactor as shown in FIG. 1 is particularly preferable.
(Residence time)
In the present invention, the residence time can be adjusted by the length of the heating zone and the flow rate of the carrier gas. The preferred residence time may vary greatly depending on the reactor used and the type of carbon compound, but generally it is preferably within 0.0001 second to 2 hours, more preferably 0.001 to 100 seconds, 0.01 to 30 seconds is most preferable. If the residence time is too short, the carbon fibers tend not to grow sufficiently. On the other hand, if the residence time is too long, many thick fibers tend to be obtained.
(Carbon recovery rate)
According to the production method of the present invention, the carbon recovery rate can be improved. Here, the “carbon recovery rate” is defined by the following equation.
[0034]
Carbon recovery rate = generated solid weight / carbon compound weight used
[0035]
【Example】
EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to these.
[0036]
In the following examples, the following reagents were used.
[Reagents]
1. Carbon compound
Benzene: Special grade reagent manufactured by Wako Pure Chemical Industries, Ltd.
2. Catalyst precursor compound
Ferrocene: manufactured by Nippon Zeon Co., Ltd.
3. Other ingredients
Polypropylene glycol: D-400 (Molecular weight: 400) manufactured by NOF Corporation
Sulfur (powder): Reagent manufactured by Kanto Chemical Co., Inc.
[Synthesis of carbon fiber]
<Examples 1 to 4 Comparative Examples 1 to 3 Reference examples 1 to 3 >
In a vertical furnace equipped with the quartz reaction tube 12 (inner diameter: 31 mm, outer diameter: 36 mm, heating zone length: about 400 mm) shown in FIG. 2, the temperature was raised to 1250 ° C. in a nitrogen stream, Instead, hydrogen and nitrogen were allowed to flow in the reaction tube at a rate shown in Table 1 as a carrier gas.
[0037]
After the temperature was stabilized, the raw material composition shown in Table 1 below was supplied from the raw material spray nozzle 1 at a flow rate of 0.1 g / min for 10 minutes using a small pump. In addition, the reaction liquid composition in a table | surface was described with the mass% in a benzene solution.
[0038]
As a result of the reaction, grayish spider web-like deposits were formed at the bottom of the reaction tube. After the temperature was lowered, this deposit was recovered, and the recovered amount was divided by the amount of benzene used to determine the carbon recovery rate. Further, the fibrous product was observed with a scanning electron microscope. The results are shown in Table 1.
[0039]
[Table 1]

[0040]
<Example 5, 6 >
Examples were used except that the gas shown in Table 2 was used at the flow rate shown in Table 2 instead of nitrogen gas. 2 The reaction was carried out in the same manner as above and the product was observed.
[0041]
[Table 2]

[0042]
<Example 7, 8 Comparative Examples 4 and 5>
Examples other than the carrier gas shown in Table 3 and the temperature of the heating zone 2 It carried out like.
[0043]
[Table 3]

[0044]
【The invention's effect】
As described above, according to the present invention, the carbon recovery rate is improved by optimizing the reducing gas concentration in the carrier gas and adjusting the reducing gas concentration in the carrier gas according to the amount of catalyst used. Carbon fiber can be manufactured efficiently and inexpensively.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view showing a general example of a horizontal reactor for producing carbon fibers.
FIG. 2 is a schematic cross-sectional view showing a vertical reactor in which carbon fibers are produced in Examples and Comparative Examples.
[Explanation of symbols]
1 ... Horizontal annular furnace
2 ... Reaction tube
3 ... Recovery container
11 ... Raw material spray nozzle
12 ... Reaction tube
13 ... Vertical annular furnace
14 ... Recovery container

Claims (5)

In a method for producing carbon fiber by contacting a carbon compound and a catalyst in a heating zone in the presence of a carrier gas containing a reducing gas;
Reducing gas concentration in the carrier gas is 35 to 70 volume%, Ri temperature 1165 ° C. to 1500 ° C. der heating zone, and the vapor grown carbon fibers, wherein the catalyst is continuously fed Production method. In a method for producing carbon fiber by contacting a carbon compound and a catalyst in a heating zone in the presence of a carrier gas containing a reducing gas;
2. The method for producing vapor-grown carbon fiber according to claim 1, wherein the logarithmic ratio of the catalyst metal concentration and the reducing gas concentration represented by the following formula is 5 or more and 340 or less.
(Logarithmic ratio of catalyst metal concentration and reducing gas concentration) = log (molar fraction of catalytic metal in reaction system) / log (molar fraction of reducing gas in reaction system) The method for producing vapor grown carbon fiber according to claim 1 or 2 , wherein the reducing gas is at least one selected from the group consisting of hydrogen, carbon monoxide, and ammonia gas. The carbon compound includes at least one selected from the group consisting of carbon monoxide, methane, ethane, propane, butane, ethylene, propylene, butadiene, acetylene, benzene, toluene, and xylene. 4. The method for producing a vapor grown carbon fiber according to any one of 3 above. The method for producing vapor grown carbon fiber according to any one of claims 1 to 4 , wherein the catalyst contains at least one element selected from the group consisting of Group 3 to 12 elements referred to in the Group 18 element periodic table.

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